Social cohesion suffers when people \emph{perceive} that they live among others
who differ from them, even if such people \emph{live} in homogeneous
neighborhoods. This paper shows that (1) two individuals who live in equally
diverse local contexts need not perceive the same amount of diversity in that
same context, nor think of the boundaries of their local community in the same
way, and (2) when comparing two individuals who live in equally diverse local
contexts, the one who \emph{thinks} she lives with more minorities tends, on
average, to see lower social cohesion and less community efficacy among her
neighbors. This descriptive finding does not show that perceptions cause social
cohesion, but our careful research design produces a finding that separates the
experience of objective social context from that of subjective context without
causal inference. Revealing that perceptions of social reality matter above and
beyond the experience of objective context adds evidence to a theory of context
effects that involves perceptions as well as experience.
